add ci/cd

.gitlab-ci.yml

+stages:
+  - build
+  - deploy
+
+pages:
+  stage: build
+  image: node:lts-buster
+  cache:
+    key: "$CI_JOB_NAME"
+    paths:
+      - node_modules/
+  script:
+    - npm install
+    - npm run build
+  artifacts:
+    paths:
+      - public
+  only:
+    - master